The chemical supercharging of racing engines has been used for some time in the racing and high performance vehicle industry for supplying a sudden burst of power to the vehicle engine for increased engine horsepower and torque. Nitrous oxide is a nonflammable liquid/gas used for such chemical supercharging which when introduced into the combustion chamber of an engine breaks down into its elements of nitrogen and oxygen. The free oxygen is then available to oxidize additional fuel that is supplied to the engine and mixed with the oxygen resulting in a large increase in power. This will provide a sudden burst of power to the vehicle for use in the final stretch of a race or for passing another vehicle at critical times in the race. Existing injection systems usually consist of a spacer plate placed under the carburetor or at the air intake on fuel injected engines. This plate carries spray bars or nozzles for introducing into the engine the nitrous oxide and the additional fuel required to maintain the proper fuel/oxygen ratio for maximum power. The nitrous oxide and fuel flow is turned on and off by solenoid valves usually located near the spacer plate or spray nozzles which also may be mounted directly in the intake manifold just ahead of the intake part in the cylinder head. These valves are controlled by a manually operated push-button switch accessible to the driver. Examples of such nitrous oxide fuel charging systems and components related thereto are shown in U.S. Pat. Nos. 4,494,488 and 4,572,140.
These prior and existing nitrous oxide fuel injection systems, although providing enhanced power when needed for a racing vehicle, possess certain problems. When the solenoid valve controlling the flow of nitrous oxide is switched to the open position by the driver, nitrous oxide under high pressure (approximately 900 psi) surges into the feed line and spray bar or nozzles where it meets resistance from restricted openings before passing as a spray into the engine intake. At this point a momentary back pressure is created in the feed line and the flow of nitrous oxide stops or is greatly diminished. This creates two problems related to power output or engine performance.
The engine sees an initial supply of nitrous oxide followed by a momentary deficiency thereof then followed by a proper and continuous flow. During this deficiency period, that can last as long as 0.30 seconds, there is no performance increase. Thus a serious reduction of power for up to 0.30 seconds results in situations where races are won by hundredths of a second. Also, at the time the nitrous oxide solenoid control valve is opened, a fuel solenoid feed valve is opened, and the additional fuel required to be mixed with the nitrous oxide flows into the spray bar or nozzles. The fuel is under a pressure of only 6 or 7 psi and no system reversion or back pressure is experienced. This means that during the momentary period of nitrous oxide deficiency, the engine is getting the additional fuel but not the nitrous oxide. This results in a rich mixture condition and resulting power loss which degrades performance to a level substantially below the engine's power potential without the nitrous oxide system. Therefore, there is a need in nitrous oxide fuel charging systems to elimiate or drastically reduce the momentary back pressure in the nitrous oxide feed line.
Another problem that exists in nitrous oxide fuel injection systems is that under certain circumstances the use of nitrous oxide or the failure of a nitrous oxide system component can cause problems for the driver and the vehicle engine. Satisfactory operation of the nitrous oxide injection system requires a proper proportion of fuel to the nitrous oxide being introduced into the engine. Should the fuel system, fuel pump, or the fuel supply fail, the engine will run lean and damage can occur to the engine pistons. Also, if the vehicle driver actuates the nitrous oxide system when the engine RPM is low, damage to the engine can occur through detonation or preignition.
For example, a given flow of nitrous oxide fuel will enter the engine upon actuation of the nitrous oxide fuel charging system whether the engine is running at 2000 RPM or 4000 RPM. However, at 4000 RPM, the engine uses approximately one-half the amount of additional power potential per cycle, reducing the additional stress on engine components by one-half in contrast to the increased stress placed on the engine upon injection of the nitrous oxide when the engine is running at an extremely lower RPM.
Another potential hazard associated with nitrous oxide fuel injection systems is failure of the main nitrous oxide control valve. Race vehicles many times are operated in contaminated environments. Failure of the solenoid valve if stuck in full open position, or most commonly in a partial open position caused by the contaminates or failure of the valve to seal properly, will permit nitrous oxide to leak past the valve and enter the intake manifold when the engine is not running and accumulate therein. Subsequent starting of the engine can cause an explosion in the manifold and possible damage to the carburetor or engine possibly resulting in explosion or fire in the engine compartment. These conditions have occurred in the past where the race driver is unaware of the failure of the nitrous oxide control valve and the accumulation of nitrous oxide in the engine when not running.
Therefore the need has existed for a nitrous oxide fuel injection system and in particular to such a system having safety features incorporated therein which eliminates or materially reduces the problems discussed above.